IT departments are hoarding thousands of abandoned and little-used applications, often referred to as “Zombie applications.”

The survey results, released today, show that if companies don’t perform a thorough spring clean of these walking dead applications, they can accrue millions of dollars in operating costs, unleash a security threat, and put overall IT performance at risk.

Over half the respondents of the survey, conducted by research firm Harris Interactive, felt that these under-performers were eating up storage space. About seven percent reported that this was costing them tens of millions of dollars in revenues per year.

The biggest revelation from an enterprise perspective is that employees aren’t actually using many applications. About a quarter responded that they used 25 or fewer on a regular basis. Other interesting insights include:

52 percent of respondents estimate that slow, crashed, or unresponsive applications cost their business at least hundreds of thousands (if not millions) of dollars per year. 31 percent said that it cost them tens of thousands of dollars per year.

In a typical day, a majority (57 percent) use fewer than half of their total applications, while 28 percent said they use fewer than 50 apps

58 percent of respondents say the performance of applications has a major impact on the performance of their business.

The research doesn’t adequately address one of the most pressing concerns. There is a major security problem that arises from the prevalence of these unused apps: they can still spread malware and, if they are set on automatic update, they can continually access information.

The survey was commissioned by Dell-owned Quest Software in June, 2012. A hundred and fifty IT professionals were polled in enterprises with more than 500 applications and $500 million-plus in revenue.